In deferred rendering the cost of lighting is still dependent on the number of lights. In forward rendering it is dependent on both the number of lights as well as the scene geometry. You can apply various additional techniques to make each light much cheaper though.
Your CPU has 4 cores, but 8 threads due to Hyper-threading. It's quite normal that not all programs will benefit from the additional threads. It would be interesting to see how the compiler performs on more physical cores.
Yes, but on the other hand rasterization is implemented in hardware on GPUs which gives it a great performance advantage. Also, sorting before rasterizing allows most triangles to be discarded before any fragments are created. Besides, creating and traversing an acceleration structure does definitely not make ray tracing free. Especially traversal is not exactly cache-friendly. Also, rays passing closely by geometry, but not hitting it, will traverse rather deep into the tree and then backtrack, which is rather costly. Another advantage of rasterization is that it is data-parallel at the vertex level. The disadvantage is that it is far less flexible in what you can render compared to ray tracing; it's only really practical for camera rays.
> raytracing an image takes much longer than the polygon-based rendering done by most game engines.
Minor nitpick, but it has nothing to do with the fact that it renders polygons. Ray tracing can also render polygons. More precisely, game engines use rasterization which works by projecting triangles onto the screen rather than tracing rays through the screen.
I can't remember if threading support is in yet, but it should be possible. The downside is that it will be a rather hefty binary the user has to download.
Indeed, the article does not represent the 2016 sales at all. Tesla sold 176 cars in 2016 in Denmark and 2738 in 2015 [0]. While there is definitely a drop, the sales of 2015 were probably also boosted by the fact that lots of Danes, who were interested in buying a Tesla, made sure to do so before the law took effect. In 2014 they sold 460.